My map is published under a CC-NC-SA license, so it is free for non-commercial use and I also require all uses to be freely accessible. mhikes.com is a commercial website and password protected. So the use of my map is clearly in violation of its open license. Unfortunately, attempts to contact mkhikes.com by mail have been ignored.

So my question to you is: Does anyone know or use mkhikes.com? Is there a better way to contact them in order to stop the mass license violation?

I sent mails to contact@mhikes.com on 20.1. and 25.1. They were in English and had about the same content as my first post above.

I have also instructed my server to block mhikes.com (meaning it returns only a blocking image instead of the requested map tiles), but for some reason I do not understand they still send about 10000 requests daily.

I was hoping to find someone, maybe a hiker, with more knowledge about that website. Talking to them on the phone might be the best idea, but I don't speak enough French to order a pizza.

We have actually been contacted by phone this morning. Since 10.30, every request to your maps has been shut down.
If you see any more request on your server, please contact me, that is not normal.

Please apologize for your unanswered mails, I found them in spambox, sorry for that.

Here are some precisions on what happened :
We are a young company and your maps where at first used as tests maps. Unfortunately they have never been removed from the website.
Technically, we use the Leaflet plugin "Leaflet Layers control with minimaps" (https://github.com/jieter/Leaflet.layerscontrol-minimap), which loads a preview of each available layer each time you display, move or zoom a map. That is why you saw a huge amount of requests on your server. We totally missed that point. Sorry.

Please note that the Mhikes application is free and without any advertisement. The website is password protected because, at the moment, only Mhikes team is allowed to create and share hikes.
We also have some professional applications but customers have to enter licence/api key if needed.

We are, I am, at your disposal if you need or want more information about what happened.
We appreciate OSM community and are entirely opened to discussion if anything we are doing is wrong, or if anyone is interested in sharing our experience.